Why is fatigue and lethargy more common in winter?

During the winter, the nights get longer as the temperature decreases, but surprisingly people face more fatigue and lethargy while often there is also drowsiness.

But why does this happen in this season?

According to experts, with the arrival of winter, there are various challenges related to sleep.

They said that during the cold season, there are changes in the level of hormones, while the exposure to daylight is less and there is also a lack of specific vitamins in the body.

So know some common reasons for fatigue and lethargy in cold weather.

Seasonal affective disorder

It is a type of depression that some people face as a result of decreased daytime in winter.

Its symptoms appear at the end of autumn or the beginning of winter and disappear when spring or summer arrives.

Most of the symptoms of this disorder are mental, but there are also some physical symptoms such as lack of physical energy, sleep problems, feeling lethargic and changes in eating habits, etc.

According to experts, this problem is more common in women than men.


They are important for physical energy. hormones called serotonin and melatonin are associated with mood and sleep.

Our brain produces melatonin so that it is possible to get good sleep in the darkness of the night, but in the winter, the darkness quickly covers and the duration of daylight is reduced, then the process of making melatonin is also affected.

In simple words, this hormone starts to become more in the morning, while in the evening, the process of its formation becomes active as soon as it is dark.

Changes in the levels of this hormone can result in negative effects on sleep and mood resulting in fatigue and lethargy.

Vitamin D

It is very important for the health of bones and teeth, while also strengthening the immune system.

Vitamin D deficiency results in fatigue.

One study found that people with vitamin D deficiency were given its supplements and their fatigue intensity was significantly reduced.

Vitamin D also supports the formation of serotonin, but its level decreases due to increased amount of melatonin in winter.

A decrease in the level of this hormone has a negative effect on mood while increasing the feeling of lethargy and fatigue.

When the duration of the day is reduced and sunlight exposure is reduced, the functions of the body clock are also affected and sleep problems are encountered.

During winter, people resort to various means to keep themselves warm, which also affects the functions of the body clock and increases sleep problems.

Lack of good sleep results in an increased sense of fatigue and lethargy.


Habits also change breakfast time in winter which affects the stability of the body clock.

According to experts, the physical clock knows when the day started, which increases alacrity and physical energy, but due to the change in times, this process is reversed i.e. laziness and fatigue.

Not exercising

Most people avoid exercising in the winter.

This in turn affects physical energy and increases feelings of fatigue and lethargy.


Author: DoctorMaryam.org

3rd Professional Medical Student. Karachi Medical and Dental College.

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